1. Field of the Invention
The present invention relates to a bobbin holder onto which a cylindrical bobbin is inserted and held thereby, which bobbin holder is mounted on a winding machine and wherein a yarn is wound onto the bobbin. The bobbin holder of the present invention is especially suitable for a winding machine for winding a spun synthetic yarn such as a polyester or polyamide yarn at a speed, for example, of several thousand m/min.
2. Description of the Prior Art
Recently, there is a trend tendency in a constructing yarn winding apparatus to reduce the diameter of a bobbin. Accordingly, the diameter of a bobbin holder is also reduced, and at the same time the length of the bobbin holder increases as its winding speed increases. Recently developed bobbin holders mounted on such a winding machine are disclosed, for example, in Japanese Utility Model Applications Laid-open No. Sho 60-43667 and No. Sho 60-1766, and Japanese Patent Application Laid-open No. Sho 55-123847.
Since a chucking member is inserted onto an outside of a supporting shaft or a holder in such conventional bobbin holders, the outer diameter of the shaft or the holder is equal to a size which is obtained from an inner diameter of the bobbin after the necessary size for the chucking member is excluded. Therefore, the outer diameter of the shaft or the holder decreases. Thus, the rigidity of the shaft or the holder is lowered, and natural vibration of the bobbin holder occurs in the operational range of the bobbin holder. Accordingly, as illustrated in FIG. 8, the vibration becomes large at an operational range above a speed of 10,000 rpm. As a result, there is a problem in that the bobbin holder cannot be rotated in such a high operational range. Accordingly, the winding machine cannot be operated at a high speed.